The present invention relates to a laser scanner, which acquires point cloud data of a predetermined range or point cloud data of an object to be measured by scanning a distance measuring light.
In a laser scanner, point cloud data of a predetermined range or an object to be measured is acquired by irradiating a pulsed light as a distance measuring light and by rotating the distance measuring light in a horizontal direction while performing rotary scanning at a constant speed in a vertical direction. The laser scanner performs a distance measurement by receiving a reflected distance measuring light for each pulse, also measures a vertical angle and a horizontal angle at the time of the distance measurement, and acquires three-dimensional data of each irradiated point (i.e. a measuring point).
A light receiving intensity of the reflected distance measuring light is under strong influence due to a measurement distance, and also, due to a condition of a surface where a distance measuring light is irradiated. Further, the light receiving intensity exerts an influence on a measurement accuracy, and an appropriate threshold value is required for a detection as to whether or not a ht is received.
Conventionally, a threshold value to detect a light receiving is fixed during a measurement. In a case where there is a change in the light receiving intensity during the measurement, there is a case where a noise may be included in a photodetection signal and an accuracy may be decreased, or a case where the photodetection signal is not acquired with respect to the object to be measured which should be measured.